Mobile phones may increase the risk of developing brain cancer, an influential
health organisation has said admitted for the first time.

The International Agency for Research on Cancer, part of the World Health Organisation, has classified the radiation emitted by handsets as “possibly carcinogenic” although it did not find evidence of a clear link.

Its decision - putting mobiles in the same risk category as lead, the pesticide DDT and petrol exhausts - will put governments under pressure to update their advice to the public on the potential dangers of talking on mobiles for long periods of time.

Christopher Wild, the director of IARC, said that while more research is carried out “it is important to take pragmatic measures to reduce exposure such as hands-free devices or texting”.

It has long been known that the radiofrequency electromagnetic fields emitted by mobile phones are absorbed by the body, much of it by the head when the handset is held to the ear.

But research into the possible health consequences of frequent mobile use has proved inconclusive because the technology has only been widely used for a few years while it can take decades for tumours to develop.

Last year a landmark IARC study, known as Interphone, disclosed that making calls for more than half an hour a day over 10 years could increase users’ risk of developing gliomas - a type of tumor that starts in the brain or spine - by 40 per cent.

Over the past eight days, a working group of 31 scientists from 14 countries reviewed the Interphone data and other studies, including a Swedish report that also found evidence of increased brain tumour risk among mobile users.

They concluded that there was “limited” evidence that wireless phones are linked to brain cancer – meaning that it could be down to chance rather than causation – and “inadequate” proof that mobiles cause other types of cancer.

Dr Jonathan Samet, chairman of the group, admitted the evidence is “still accumulating” but insisted: “The conclusion means that there could be some risk, and therefore we need to keep a close watch for a link between cell phones and cancer risk”.

By classifying mobiles as “possibly carcinogenic”, the IARC has placed them alongside DDT, chloroform, coffee, lead and working as a firefighter in a list of more than 900 agents it has analysed. However this is only the third-highest rating, below “carcinogenic to humans”, which includes cigarettes, and “probably carcinogenic”, which includes diesel exhausts and creosote.

But with an estimated 5 billion mobile phones in the world, health agencies are likely to act on the IARC’s warning, which will now be discussed by the World Health Organisation.

As The Daily Telegraph disclosed in March, the Department of Health in England recently updated its advice to the public by saying that sending text messages or using hands-free kits can reduce exposure to radiation, by keeping the handset away from the head.

It is also recommended that children only use mobiles when strictly necessary, as they are at greater risk of absorbing radiation.

Following the IARC’s announcement, experts pointed out that it did not prove mobiles cause cancer, and that there was still little long-term research on the subject.

Ed Yong, head of health information at Cancer Research UK, said: “The risk of brain cancer is similar in people who use mobile phones compared to those who don't, and rates of this cancer have not gone up in recent years despite a dramatic rise in phone use during the 1980s.

“However, not enough is known to totally rule out a risk, and there has been very little research on the long-term effects of using phones.”

Prof Malcolm Sperrin, Director of Medical Physics & Clinical Engineering at Royal Berkshire Hospital, said the categorization was justified but added: “It should also be stated that electromagnetic field exposure is not new - witness the regular usage of radio and other waves for many decades with no convincing health detriment at low powers. The social and technological benefits also need to be emphasised.”

John Cooke, Executive Director of the Mobile Operators Association, said: “It is important to note that IARC has not established a direct link between mobile phone use and cancer. It has, however, concluded that there is the possibility of a hazard. Whether or not this represents a risk requires further scientific investigation.”